Brake



Mmh 8,1938. H. F. DOTY 2,110,291

' BRAKE Filed Feb. 17, 1936 Il, m "Will/11111 BY am M ATTORNEY.

Patented Mar. 8, 1938 @UNiTao smits earner orties 2 Claims.

The invention relates to brakes such as used in connection withautomobiles and more particularly to the construction of such brakes, asare classed generally as mechanically or hydraulically operated.

An object of the invention is to provide a brake of the characterdescribed which will embody both a direct mechanical and a hydraulicoperation, the former for insuring a degree of posi- .tiveness in theoperation of the brake, and the latter for providing .an equalapplication of braking force to each of the wheels of the vehicle.

Another object of the invention is to provide a brake of the characterdescribed in which the mechanical or hydraulic actuating means will beso arranged as to augment the operation of the other and provide forpositive .actuating of the brake in the event of the failure of eitherof these mechanisms to operate.

A further object of the invention is to provide a brake of the abovedescribed character, which will be self energized to the extent oftransferring a part ci the kinetic energy of the moving vehicle intobraking energy and thereby greatly increasing the available brakingpower with a minimum expenditure of energy by the operator of thevehicle.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of the preferred form of the invention which is illustratedin the drawing accompanying and forming part of the specification. It isto be understood, however, that variations in the showing made by thesaid drawing and description may be adopted within the scope oi theinvention as set forth in the claims.

Referring to said drawing:

Figure 1 is a vertical sectional view of a brake constructed inaccordance with the present invention in partially applied position.

Figure 2 is a transverse sectional View of a fluid expansion chamberconnecting certain shoes of the brake apparatus and is takensubstantially on the plane of line 2 2 of Figure 1.

Figure 3 is a transverse sectional View of a pivotal connection betweenthe ends of certain of said brake shoes and is taken substantially onthe plane of line 3-3 of Figure 1.

Figure 4 is a transverse sectional View of one of the supporting meansfor the several brake shoes and is taken substantially on the plane ofline rl-G of Figure 1.

Figure 5 is a transverse sectional View of another brake shoe supportingmeans and is taken (Cl. 18S-e152) substantially on the plane of liner5-5 of Figure l.

Figure 6 is a transverse sectional View of the mechanical actuatingmeans for the brake and is taken substantially on the plane of line 6 6of Figure 1.

rlhe brake, as illustrated in the accompanying drawing is in part ofmore or less standard construction including a rotary brake drum I, astationary brake plate 3 mounted opposite thereto and a plurality ofbrake shoes 9, II and I2, which are supported on plate 8 incircumferential relation to the drum and are arranged for movementagainst the drum 'I for checking its movement. 'I'he shoes are formedwith an outer cylin-v drical portion I3 which is backed by a radiallyextending rib lli and carries a brake lining I4. Means for supportingthe shoes on the plate 8 consist of an anchoring stud I'I which supportsthe adjacent ends I8 and I9 of the shoes II and I2, while the other end2| of shoe Il is pivotally connected by means of a pin 22 with theadjacent end 23 of the shoe 9 and the opposite ends 24 and 26 of 'theshoes 9 and I2 are interconnected by a hydraulic means 2l. The shoes 9vand II are further supported and held in proper position by means cimounting devices each consisting of a projection 2S on the backing plateB and which threadably carries a stud 29 engaging at its outer end in amember 3| carried on the rib I6 of the shoes for adjusting the radialposition of the shoes. A nut lock 32 may be carried on the inner'end ofthe studs. As will be clear from Figures I and 5 the members 3l arepreferably slotted to straddle the rib I6 and afford a pivotal movementtherebetween in the plane of the rib while the outer end of the stud isslidably carried in the member 3| thus permitting both a radial and acircumferential movement of the shoes. The shoes are normally held inretracted y position and spaced from the drum by means of springs 33secured to the projection ,28 and the rib i6 of the shoes. A similarretraction of the shoe I2 is effected by means of a pair of springs 34,which are connected between the rib of the shoe and a projection 36 onthe brake plate.

As will be clear from Figure 4, the end I8 of the shoe I I is bifurcatedand slotted so as to surround and abut the stud Il and anycircumferential force on the shoe I6 through the pivotal connection 22to the shoe l l will be checked by the stud and such force therebytranslated into an outward movement of the shoes 9 and I I against theinner circumference of the brake drum. In accordance with the presentinvention this crcumferential force is arranged to be set up andther'brake thereby applied by the use of the shoe I2 and a manuallyoperated means for pressing the shoe against the inner side of therotating drum. As here shown, this means consists cfa shaft 31 which isslidably carried by the projection 38 and which extends therethrough andis connected at its outer end to a roller 39 engaging the inner edge ofthe rib I6 of the shoe I2. Actuation of the shaft 31 is eifected throughmeans of a lever 38 which, may in turn, be connected to the foot pedalor the like (not shown) of the vehicle. It will thus be clear that withdrum rotating in a counter-clockwise direction,

with reference to Figure 1, the pressing of the shoe I2 against the drumwill set up a circum- V ferential force which is transmitted through thehydraulic means 21 and expands the brake shoes` 9 and II against theinner circumference of the drum. The hydraulic means 21, as shown inFigure 2, comprises a cylinder 4| in which are reciprocately carried apair of pistons 42 and 43, which slidably carry, in slots at their outerends,

the ends 26 and 24 respectively, of the brake shoes *f braking forcetransmitted through each hydraulic means'of the several brake units willbe'equalized. The hydraulic brake system above described is connected tobe actuated by the-brake pedal which operates lever 38.

' As an important safety feature of the present invention, should one ofthe fluid lines of the brake ysystem sever and theiiuid escape, the pis-Vton head 41 will move directly against the head 48 and provide a directphysical connection between `the shoes I2 and 9 and thus cause the braketo operate notwithstanding the loss of iluid. On,

the other hand, should one of the manual connections operating thelevers 38, break, the operation of theY other brake units will establisha 50iiiuid pressure inthe hydraulic cylinder of the defective brake andthereby transmit to this brake a braking force equal to that applied tothe other brakes.

Operation of the brake during the reverse movement of the vehicle isalorded by a some-` what reversed movement of the several parts. As willbe clear from Figure 4, the end I9 ofthe shoe I2 is slotted to surroundthe stud I1 and engage in the socket provided by the bifurcated end I8of the shoe I I. On the other hand, the end 24 of the shoe 8 isl mountedin proximity to the end I of the hydraulic cylinder and is arranged tomove thereagainst upon a clockwi circumferential displacement of theshoes. Thus, with the i vehicle in reverse, and the shoe I2 pressedagainst the brake drum, the circumferential force of the brake shoe I2will be transmitted through the engaged ends I9 and I8 of the brakeshoes I2 and II to rst move the end 24 of shoe 9 against the end of thecylinder and then cause a radial expansion of the shoes 9 and II againstthe inner circumference of the drum.

It will now be clear that by reason of the manually operated brake shoeI2 and the connection aiorded between this shoe and the vother shoes yregardless of whether the hydraulic means is in operation, an extremelypositive and reliable brake is provided. Also in combination with thispositiveness and safeness in operation, the innerpositioning of thehydraulic means insures the application of an equal braking pressure toeach AAf lthe brake units. Furthermore, and as an important feature ofAthe present invention the actual operating force is, for the most part,taken from the rotating brake drum itself by the frictional drag of thedrum against the shoe I2 and in this manner the kinetic energy of themoving vehicle is employed to cause a braking of the vehicles movement.This self energizing feature of the brake, as will be understood,provides a powerful braking action While reducing the manual forcerequired of the operation to a minimum. Y

When the cylinder is filled with fluid and the shoe I2 is mechanicallybrought into contact with the rotating drum, the piston 42 vis moved tothe right, as'viewed in Figure 2, and such movement forces the fluid inthe cylinder to the right thus increasing the pressure againstthefpiston 43, and thereby increasing the pressure exerted on shoe 9.

I claim:

1. A brake mechanism for a brake drum or the like comprising, a brakeshoe, mechanically operated means for moving said shoe against saiddrum, a secondbrake shoe, hydraulic means comprising a cylinder andpiston connected between said shoes and containing fiuid in saidcylinder for moving said second shoe against said drum on movement ofsaid first shoe by said mechanically operated means, said hydraulicmeans being provided with opposed portions engageable fordirectlytransmitting movement from said rst to second named shoe in theabsence of said fluid.

2. A brake mechanism foreach of a plurality of brake drums comprising, aplurality of brake shoes movable against said drum, one of said shoesbeing circumferentially displaceable rela.- tive lto said drum,mechanically operated means for moving said last named shoe against saiddrum, and hydraulic means for transmitting the circumferential force onsaid last named shoe on engagement thereof with said drum to said othershoe',land being adapted for connection to the similar hydraulic meansof the other brake mechanisms to equalize the force transmitted fromeach of the circumferentially displaceable shoes to the other shoe,said' hydraulic means comprising a cylinder, apair of opposed pistons insaid cylinder connectedl to said circumferentially dis placeable Shoeand said other shoe and operative on fluid therebetween to transmitforce between said-shoesand' being' adapted to abut in the absence ofsaid fluidto'transmit said force by direct contact with each other.

HAROLD F. DoTY.

